1. Field of the Invention
This invention relates to a starter for starting an engine. More particularly, this invention relates to a brush device for starters.
2. Related Art
Among conventional starters, as shown in Japanese Utility Model Publication No. Showa (JU-A) 63-71474, a coaxial-type starter provided with a motor and a pinion rotatably disposed axially in front of the motor to be driven by the motor and a magnet switch disposed adjacent to the rear portion of the motor is described.
In this starter, a coaxial construction is used, with a plunger of the magnet switch passing through the inside of a rotary shaft of the motor and axially biasing the pinion in front of the motor. If such a construction is adopted, due to the disposition of the magnet switch behind the motor, the required area as viewed from the axial direction of the starter can be markedly reduced compared to conventional starters wherein the magnet switch is disposed on and in parallel with the starter motor.
However, in conventional starters, used is a face-type commutator in which each brush is pressed to the commutator in the axial direction by a coil spring. In order to obtain the specified spring strength, a sufficient spring length is required and, as a result, the axial length and magnet switch length overlap thereby causing a remarkable increase in the axial direction for installation.